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evildragon

Veteran Member
Joined
May 29, 2007
Messages
1,646
Location
Tampa Florida
Haha, another forum I know, an audio forum, has a thread like this, you post your systems insides, hence nudies.

in this case, show off the insides of your vintage computers. i've always been fascinated by the circuits and wiring.

here's my model 25, with all cards removed (SB16 and VGA card), and internal CRT wired up to onboard graphics..

http://img.photobucket.com/albums/v395/Evilweredragon/m25/6.jpg

My model 25 VGA hack:
http://img.photobucket.com/albums/v395/Evilweredragon/vgamod1.jpg
http://img.photobucket.com/albums/v395/Evilweredragon/vgamod2.jpg
http://img.photobucket.com/albums/v395/Evilweredragon/vgamod3.jpg
 
That's the first XT-class machine I've seen using SIMMs. Actually, 256K in DRAM chips on the motherboard, plus two 256K SIMMs, for a total of 768K... of which only 640K is actually used.

Is the video quality good without any shielding on those wires? The analog signals of VGA are more prone to interference than digital video (CGA/EGA), thus most VGA cables are fully shielded and use an RF choke (that's the cylindrical "blob" on the cable).
 
I added that ferrite block myself.

The video quality is great, nice and crisp. 16 shades of grey in 640x480 now, instead of the 2 shades before (black and white). Also gained some new resolutions, 360x480 256 shades of grey, and 640x400 (forget how many shades of grey).
 
evildragon said:
I added that ferrite block myself.

The video quality is great, nice and crisp. 16 shades of grey in 640x480 now, instead of the 2 shades before (black and white). Also gained some new resolutions, 360x480 256 shades of grey, and 640x400 (forget how many shades of grey).
Click to expand...
Actually, VGA monochrome is limited to 64 shades of gray.
 
Is the 64 shade limitation caused by the inability of a black and white display of not being able to produce visual differences between the R, B and G signals?
 
I combined the RGB values into a single un-weighted luma signal.

The VGA card is jumpered into thinking it's in COLOR mode. When in 256 colors, it can infact produce 256 shades of greys. I've tested this, especially when I load a palette of 256 levels of grey..

See.. If you don't believe me, write a program, and have me photograph it for more proof. I got a good camera. This was in 360x480 resolution.

64 Shades of Grey
http://img.photobucket.com/albums/v395/Evilweredragon/64.jpg

256 Shades of Grey
http://img.photobucket.com/albums/v395/Evilweredragon/256.jpg

Source images...

64 Shades
http://img.photobucket.com/albums/v395/Evilweredragon/64-1.gif

256 Shades
http://img.photobucket.com/albums/v395/Evilweredragon/256-1.gif

I'm not so sure though that the VGA palette can associate enough shades of grey though. BUT! Since they are unweighted RGB combinations, you can mix some colors up to give another shade of grey. I do this in Windows. For an ultra light shade of grey, I use yellow.

PS: Some photos on it in 360x480. Sure looks like 256 shades to me.

http://img.photobucket.com/albums/v395/Evilweredragon/car.jpg

http://img.photobucket.com/albums/v395/Evilweredragon/bottle.jpg
 
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Here's my CompuAdd 810 stripped down (ISA cards, hard drive, and floppy drive cage removed).

General inside view:
http://img.photobucket.com/albums/v93/zzm113/compuadd/HPIM0696.jpg
9.54 MHz NEC V20, empty 8087 socket, Award XT BIOS (with built-in support for 1.2/1.44 MB floppy drives!), empty user BIOS socket (I'm tempted to add an IBM Cassette BASIC ROM), 640 kB of 120 ns RAM onboard, piezo beeper.

Closeup of motherboard:
http://img.photobucket.com/albums/v93/zzm113/compuadd/HPIM0690.jpg
Dallas DS1287 clock chip with dead internal battery, onboard HD floppy controller, and yes, onboard IDE! It's IDE-XT, though, so only a handful of drives will work with it.

Closeup of rear corner of motherboard:
http://img.photobucket.com/albums/v93/zzm113/compuadd/HPIM0693.jpg
The two extra ISA slots on the other side of the riser have limited usability; the power wires, floppy/hard drive cables, and game port cable get in the way, and you have to remove the power supply to install or remove cards in those slots.

Rear of the case:
http://img.photobucket.com/albums/v93/zzm113/compuadd/HPIM0699.jpg
The power supply is a standard "so-called-PS/2-type" (145 Watts). Ports for keyboard, parallel, COM1 and COM2 serial, and MDA/Hercules or CGA video along the bottom, and the "optional" game port a bit higher up (a stock 810 doesn't come with the game port, but the functionality is there on the motherboard; all you need is the port itself with a cable to connect it).

Front of case with floppy drives installed:
http://img.photobucket.com/albums/v93/zzm113/compuadd/HPIM0703.jpg
Originally it only had the 5¼" 360 kB drive. I installed a generic 3½" 1.44 MB drive and it works fine, but doesn't quite look right because CompuAdd used a non-standard half-height 3½" drive. I cut part of the original blank trim piece to fill in the gap. The power switch is on the right side of the front panel, and there's a green hard drive LED behind the translucent 810 logo. The CompuAdd logo is engraved into the case and looks really nice! The half-height 3½" hard drive bay hides underneath the two floppy drive bays.

CompuAdd used the same basic case all the way through their early 486 models. They later made a wider version of it, with two side-by-side 5¼" floppy/CD-ROM drive bays, instead of one 5¼" and one 3½".
 
I have a CompuAdd 316s I believe which is the wide version. I never saw a desktop so thin and wide until I came across it. I also have a CompuAdd 433 which is gigantic. Roughly as wide as the above mentioned one except 3x 5.25 bays tall and HEAVY! CompuAdd always used a good, solid chassis. A little rough to heft around but good machines.
 
Vlad said:
I have a CompuAdd 316s I believe which is the wide version. I never saw a desktop so thin and wide until I came across it. I also have a CompuAdd 433 which is gigantic. Roughly as wide as the above mentioned one except 3x 5.25 bays tall and HEAVY! CompuAdd always used a good, solid chassis. A little rough to heft around but good machines.
Click to expand...
This was their "Full Profile" desktop case. All eight slots can accomodate full-length boards!

15hbh4k.jpg


3130igp.jpg


2d8l061.jpg


This was their full AT size 386/486 combo EISA motherboard... sixteen 30-pin SIMM slots, two BIOSes, two Dallas DS1287 clock chips!

29lxr1s.jpg


(None of this is mine; all photos taken from current eBay auction pages.)
 
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aw, i already had my camera on and my pants down. please do not make misleading thread titles in the future. i like this idea though! nifty, i'm going to take some pics. (of the computers, not me)

that model 25 is very neat, never seen inside one before. from the gold color on the CPU, i am thinking that's an AMD chip? or is that NEC...
 
Two dallas chips?!?! What a pain in the ass that must be. There's nothing I hate more than dallas chips, because after they die they render the board practically useless since it's next to impossible to get a replacement. The DS1287 chips aren't too difficult to find, but most of those EISA boards use far less common dallas chips that have no suitable replacements. There are ways to replace the batteries inside of dallas chips but involves cracking or drilling the damn things opened. I tried it twice, and ended up destroying the chip in the process both times since the legs on them are made out of shitty tin.

That's a damn nice EISA board otherwise. Do you think the smaller socket is really for a 386 or for a Weitek chip? Later I'd really like to built a nice EISA 386 system.
 
one of my XT clones. this one is made by BMI. (my other XT clone is a motherboard made by "PC's Unlimited" who changed their name a few years later to... DELL. i believe it is the first board "dell" ever made.) it's probably my favorite toy as far as old computers go.

all the cards other than the MFM disk controller right now.

xtclone1.jpg


xtclone2.jpg

^ pulled out the HDD controller here, so you can get a peek at what was behind it.

xtclone3.jpg


and yes, that IS a sony CD-RW drive lol. i was screwing around recently, connecting it to a tertiary IDE connector on an old ISA board... wanted to see if i could get MSCDEX to recognize it... i didn't really have much luck, and i gave up soon. i have just been too lazy to pull it back out.

if i somehow get the 8088 to burn a CD, i WILL BE YOUR NEW GOD but the possibility seems bleak.
 
Hmm...it just may be possible to burn a CD on an XT. I know that there is burning software written for DOS, but I have no idea what kind of CPU it was compiled for.

I would say that if you wanted to do it, SCSI would be the way to go. I have my doubts that you'll be able to find an IDE controller for an XT that supports ATAPI drives. Assuming there is burn software that will run on an 8088 I think it should work as long as you keep the burn speed down. I think anything more than 2X would be risky. 8MHz XT bus can do 500-600kb/sec, but I am not sure if those rates are sustainable.
 
Anonymous Coward said:
Two dallas chips?!?! What a pain in the ass that must be. There's nothing I hate more than dallas chips, because after they die they render the board practically useless since it's next to impossible to get a replacement. The DS1287 chips aren't too difficult to find, but most of those EISA boards use far less common dallas chips that have no suitable replacements. There are ways to replace the batteries inside of dallas chips but involves cracking or drilling the damn things opened. I tried it twice, and ended up destroying the chip in the process both times since the legs on them are made out of shitty tin.
Click to expand...
I couldn't resist. :D

2ljqerc.jpg
 
i wish i something more interesting to show you guys than an old run of the mill dime a dozen XT clone... i could snap shots of a huge 286 motherboard, but thats even less interesting.

maybe i should go back to the no pants and camera thing again... at least that would be interesting.
 
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